https://doi.org/10.1351/goldbook.15781
- Similarity of anatomical structures in different species because of shared ancestry
- Similarity of DNA or RNA nucleotide sequences, or of protein amino-acid sequences, supporting the hypothesis that they share a common ancestor.
Note: Homology among DNA or RNA nucleotide sequences, or among protein amino-acid sequences, is often concluded on the basis of sequence similarity. In general, if there are almost identical sequences, it is likely that they are homologous. However, it is possible that highly similar sequences were not derived from a common ancestor, i.e., they are similar but not homologous.